The present invention is related to a fluid filter having a filter element sealed inside a canister, also called a spin-on type fluid filter. These types of filters are commonly used in lubrication systems of automotive or stationary internal combustion engines that require uninterrupted oil lubrication for moving parts. In these systems, continually filtered oil is supplied through the fluid filter as part of a lubrication circuit.
Conventional designs of conventional fluid filters, such as a typical spin-on or canister sealed fluid filters, include components that are made both of metallic and non-metallic materials that support the main function of filtration performed by the filter element housed inside the filter's can. A typical conventional fluid filter assembly is shown in FIGS. 5A and 5B. The filter includes multiple components and parts that have to be assembled in successive steps, resulting in many no-value added processes. These no-value added processes waste resources and increase the cost of the filter.
The conventional filter element may be a media element 11 which has the main function of filtrating the fluid, is housed in a can 12, and is attached to the threaded plate and retainer assembly 13 to provide a mounting arrangement on the mounting base of an engine. The thread plate assembly 13 has inlet holes 14 used to provide the unfiltered or dirty oil to the filter housing, arranged around a bolt circle diameter surrounding the central thread hole 15. The central hole 15 is used as an outlet of clean, filtered oil from the spin-on filter when the engine is operated.
Typically the oil flows to the filter housing under a design pressure and flow rate delivered by the engine's oil pump (not shown). The filter is mounted on a thread stud (not shown) which fastens to the central thread hole 15. The assembly has a conduit path designed to return the filtered oil from the inner core of the filter element back to the moving or stationary parts of the engine that need continuous lubrication under varied operating conditions.
The anti-drain back valve 16 in the conventional design includes a cup shaped rubber cone 17 covering the inlet holes 14 of the thread plate 13, used to help retain the fluid (in this case oil) in the housing/can when the engine is turned off. This is an important requirement when the filter is mounted with the case dome up and the threaded plate downwards, or in any horizontal or other mounting orientation where the oil would normally exit the can by gravity. When the engine starts, the rubber conical flap 17 unseats from the inlet holes 14 due to the force of the pressurized supply of fluid, and allows the flow of fluid into the filter housing.
When the lubrication pump and/or the engine are turned off, the conical round flap 17, which forms the anti drain back valve, seats back on the circumferential seat 18 of the metal threaded plate to prevent the flow of oil from draining out of the filter through the inlet holes. This helps retain the oil or other fluid in the filter housing. Benefits of this feature include preventing the filter from drying out, and air from being trapped in the oil piping. In addition, as the engine is started, the required oil flow is achieved instantly, without any air pockets being formed in the lubrication circuit.
In conventional filter designs currently in production, a filter media element 11 may include a bottom spring support or an element guide 19 to provide sealing of the inlet to the outlet by cushioning the design stack-up tolerances of various assembly components. This may be achieved by using compression spring or element guide type supports, as shown in FIG. 5A. The conventional end sealing cap may be a plastic or metal cap 20 used to seal the filtration element made of filter media 11. The end cap 20 provides a seat for a relief or by-pass valve which includes an assembly of multiple components such as a spiral or compression spring 21, a piston 22 and U-clamp 23 that are welded or riveted to the end cap to hold all the components together. This configuration also allows the relief or bypass valve to function (see FIG. 4) by allowing the fluid to bypass the filter elements if the filter becomes clogged.
End cap assemblies of the can 12 generally include several other components. The described relief valves may be disposed on a thread side (inlet side) of the filter, on the top end caps or on the bottom side caps of the filtration elements. The relief valve is used in the filter element to provide lubrication oil in the event of cold starting conditions, when the engine is turned-on after being off for extended periods of time and the fluid is so thick that it does not flow easily, or when the filtration media becomes clogged by excessive usage or excessive dirt in the oil. The relief valve or by-pass valve opens when a pre-set pressure differential has built-up in the filter, to connect the inlet to the outlet without passing through the filtering media, and prevent lubrication starvation of the engine.
A conventional filter of the spin-on type is generally constructed using the following components, to achieve the desired filtration function. With reference to FIGS. 5a and 5b, the conventional filter includes:                Filter housing 12.        Thread Plate with retainer 13 for assembly with the filter housing 12.        Seal gasket 10.        Filter Media element 11 with supporting Center tube 9.        Anti Drain Back Valve (ADB) 16.        Relief valve (RV) 08.        Bottom support 19.        
The following supplementary components that constitute the internal parts and/or assemblies of the conventional filter are also generally required:                Bottom spring/element guide 19.        Relief valve housing 23.        Relief valve spring 21.        Relief valve piston 22.        End cap Bottom/Top 20.        Welding or riveting process for Relief valve assembly 31.        Bonding with adhesive 32 of metal or plastic cap to filter element and thermal curing process thereof.        
According to the exemplary embodiments of the invention, the additional components described above are replaced by a single-piece, resilient end elements of the filter. Several manufacturing processes used conventionally to assemble the additional filter components are also avoided, further simplifying and reducing the cost of the process. As will be described in greater detail below, specially shaped integrated components formed from resilient materials, preferably assembled using interference fitting to retain the parts together, define the cap and the bottom support of the filter. In one exemplary embodiment, the end cap may also define the relief valve, an end seal, and a bottom support for the filter media. Another exemplary end cap may define the anti-drain back valve and an end seal.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.